1. Field of Invention
The invention relates to image processing technology, and more particularly to a method for increasing speed in virtual 3D application.
2. Related Art
Recently, the technology is advanced. So, a conventional game console having a flat image display is gradually replaced with another game console with 3D image processing. FIG. 1 is a schematic illustration showing a concept of simple 3D image processing applied to a conventional game console. As shown in FIG. 1, a tile 11 on the floor in a lower portion of a frame 101 is larger than a tile 12 in an upper portion of the frame 101 so that the distance difference can be seen from the drawing. Correspondingly, a user (player) can imagine that he or she stands on the floor at the lower portion of the frame and looks forwards. Basically, the concept of this virtual 3D image processing is to achieve the effect of simulating the floor in the 3D space according to the two-dimensional (2D) plane by adjusting the scaling ratio of each scan line.
FIG. 2 is a schematic illustration showing calculations of the 3D image processing of FIG. 1 in the conventional game console. As shown in FIG. 2, before a first scan line S1 is outputted, an interrupt instruction is sent to a processor in the game console so that the processor starts to calculate a scaling parameter and a rotating parameter corresponding to the first scan line S1 and stores the scaling parameter and the rotating parameter into a share register 20. Next, after the first scan line S1 is outputted, a horizontal blanking period H-Blank is entered, the interrupt instruction has to be outputted again so that the scaling parameter and the rotating parameter corresponding to a second scan line S2 can be calculated and stored to the share register 20 to overwrite the scaling parameter and the rotating parameter originally stored in the share register 20. The processes are repeated until the frame is completed calculated. In brief, all the scan lines share the same scaling register and the parameters stored in the scaling register are updated after each scan line ends in this method.
However, the calculation is made according to 262 scan lines refreshed 60 times per second in a standard television. So, the number of times of interrupting the internal processor is equal to 60×262=15720. The virtual 3D technology is usually used in a portable game console, which has the processor and the power consumption that are restricted. Thus, when the process is interrupted too frequently and the interrupt delay of the system is too long, the delay of the game may occur. In addition, the processor, which is often in the busy state, causes the too-high power consumption so that the lifetime of the battery is shortened.